MOBILE COMMUNICATION SYSTEM AND MOBILE STATION PERFORMING DIVERSITY HANDOVER

• US 20090011766A1
• Filed: 06/18/2008
• Published: 01/08/2009
• Est. Priority Date: 06/04/1997
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Sato, Takaaki, Tamura, Motoshi, Ohtani, Tomoyuki
• Granted Patent: US 8,064,908 B2
• Time in Patent Office: Days
• US Class Current: 455/437
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/28 involving a plurality of connections, e.g. multi-call or multi-bearer connections
• CPC Class Codes: H04W 36/302 due to low signal strength
• CPC Class Codes: H04W 92/04 Interfaces between hierarchically different network devices
• CPC Class Codes: H04W 92/20 between access points
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A mobile station for communicating with base stations simultaneously in diversity handover. The mobile station monitors radio condition quality corresponding to a plurality of branches, selects one or more addition branch candidates based on the monitored radio condition quality. The mobile station arranges the addition branch candidates in order of the monitored radio condition quality; notifies a center of information on said plurality of branches including said addition branch candidates, the addition branch candidates being notified in the arranged order. Alternatively, the mobile station obtains a relative value of each of the addition branch candidates indicative of order of precedence to be used for the diversity handover based on the monitored radio condition quality of said addition branch candidates; and notifies a center of information on said plurality of branches including said addition branch candidates and their relative values.

Claims

1. A mobile station for communicating with a plurality of base stations simultaneously in diversity handover, said mobile station comprising:

means for monitoring radio condition quality corresponding to a plurality of branches;

means for selecting one or more addition branch candidates based on the monitored radio condition quality;

means for arranging said addition branch candidates in order of the monitored radio condition quality; and

means for notifying a center of information on said plurality of branches including said addition branch candidates, said addition branch candidates being notified in the arranged order.

2. A mobile station for communicating with a plurality of base stations simultaneously in diversity handover, said mobile station comprising:

means for monitoring radio condition quality corresponding to a plurality of branches;

means for selecting one or more addition branch candidates based on the monitored radio condition quality;

means for obtaining a relative value of each of said addition branch candidates indicative of order of precedence to be used for the diversity handover based on the monitored radio condition quality of said addition branch candidates; and

means for notifying a center of information on said plurality of branches including said addition branch candidates and their relative values.

3. A mobile station as claimed in claim 2, further comprising:

means for selecting one or more deletion branch candidates based on the monitored radio condition quality;

means for notifying said center of said deletion branch candidates; and

means for deciding whether there is room for additionally establishing one or more communicating branches for the diversity handover, wherein said mobile station notifies said center of all of said addition branch candidates and their relative values, if there is room for additionally establishing one or more communicating branches for the diversity handover.

4. A mobile station as claimed in claim 3, wherein said mobile station decides that there is room for additionally establishing one or more communicating branches for the diversity handover, when there are one or more deletion branch candidates, or the number of communicating radio branches is less than the maximum number of radio branches which can be established simultaneously.

5. A mobile station as claimed in claim 2, wherein when the number of communicating radio branches is equal to the maximum number of radio branches which can be established simultaneously, said mobile station notifies said center of only addition branch candidates whose radio condition quality is better than that of the lowest priority communicating branch by more than a predetermined threshold value, and their relative values.

6. A mobile station as claimed in claim 2, further comprising:

means for selecting one or more deletion branch candidates based on the monitored radio condition quality;

means for autonomously releasing communication branches of said deletion branch candidates; and

means for notifying said center of the release of the communication branches.

7. A center of a mobile communication system being connected to a plurality of base stations and communicating with a mobile station via the base stations, said center comprising:

means for receiving information on one or more addition branch candidates, said addition branch candidates having been arranged in order of radio condition quality by said mobile station and notified from said mobile station in the arranged order; and

means for establishing one or more communicating branches for diversity handover by trying to establish those one or more communicating branches by using said notified addition branch candidates in the arranged order.

8. A center of a mobile communication system being connected to a plurality of base stations and communicating with a mobile station via the base stations, said center comprising:

means for receiving information on one or more addition branch candidates and a relative value of each of said addition branch candidates indicative of order of precedence to be used for diversity handover, said addition branch candidates and their relative values having been notified from said mobile station; and

means for establishing one or more communicating branches for the diversity handover by trying to establish those one or more communicating branches by using said notified addition branch candidates in the order indicated by their relative values.